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How Dyson made its bladeless fan 75 per cent quieter

Dyson engineers found that the first generation of fan wasn't as efficient as it could have been. Here, the fan is undergoing acoustic testing

Dyson

When Dyson released its first Air Multiplier fan back in 2008, the company had a couple big goals: to make one of the quietest fans on the market, and make it without any blades. The fan that hit stores was a perplexing little contraption, with a thin circular head that blew air out of tiny holes dotting its perimeter.

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It was quiet at first -- the gadget emitted a noticeable hiss -- but then very loud once you started to live with the thing. "We got feedback and people were saying the fan was pretty noisy," recalls John Baptiste, a sound engineer with Dyson.

This was an issue. For a company that sets a premium for pushing the boundaries of everyday objects, even a little unwanted noise undermines Dyson's ambitions, and reminds the consumer that they're not quite the magically functional devices that Dyson has touted for so long. As the company set out to work on the second generation of the Air Multiplier (now available), the engineers had a new goal: find what was causing the problem noise area and fix it.

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"We analysed all the different bits of our fans, and realised they weren't that efficient after all," he says. In the original model, the air is generated via a motor and impeller in the base of the device and pushed up through the circular head where it exits out the slits. The air was supposed to transition smoothly from base to loop, but that wasn't happening. Instead, air would launch upwards and hit the top of the fan's wall before funnelling towards the circle. This inefficient airflow created turbulence which in turn taxed the motors and ultimately made for a louder, power-hungry device.

If you look at the second generation of the Air Multiplier, they look more or less the same. In order to eliminate the noise, Baptiste and his team realised they had to redesign the guts of the fan. "In the beginning we investigated different layouts," he says, adding they toyed with idea of changing the head's geometry or altering the size of the air holes. "But in the end we found that we had to redesign the inside of the product," he says.

A massive energy savings

Baptiste began by smoothing out the loop to improve airflow and reduce stress on the motor. This meant the fan could now produce the same amount of air with half the energy used before. They also built in a feature called a Helmholtz cavity, which is essentially a little hole where the motor and impeller sit. "This makes the motor quieter and sound nicer," explains Baptiste.

This idea -- making sure a device's sound is not only quiet but pleasant -- is often overlooked. It's easy to assume that as long as a fan is quiet, that's all that matters. Not so, says Baptiste.

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During testing he found that the new generation was emitting a sound with a frequency of 1000 hertz. This particular frequency, often described as a high-pitched mosquito buzz, is inarguably annoying. Since Dyson wasn't able to change the frequency coming from the motor, they decided to trap it inside the Hemholtz cavity.

Dyson claims the new Air Multiplier is 75 per cent quieter than the previous generation, which really is a substantial decrease in noise. The fan isn't completely silent, which is actually a blessing in disguise for nit-picky Dyson engineers who are constantly working out the bugs in earlier models. In fact, says Baptiste, his team is already finding ways to improve on what they just released. "When we release a new product, you can be sure we're already working on the next generation," he says. "And maybe even the next generation after that."